Same problem here, can't open system settings.
sudo eopkg install gnome-control-center
is done, but in journalctl occures:
Mär 11 12:08:09 phoebe us.getsol.budgi[2038]: g_app_info_launch: assertion 'G_IS_APP_INFO (appinfo)' failed
After try to open system-settings.
Which package contains the c_app_info_launch? Is there a way to get information which files are in a package? Something like 'equery files gnome-control-center' on my Gentoo-System. But I can't see there because I have not Gnome installed on Gentoo, but XFCE4